KABUL, Afghanistan, and LONDON -- Britain, the United States' staunchest ally in Afghanistan, has suffered its worst single battlefield loss in six years, testing a strained coalition's commitment to ensure that Afghan security forces can take over the task of fighting the Taliban.
Six British troops were presumed dead after a massive blast destroyed their heavily armored vehicle in Helmand province, Western military officials said Wednesday. The fatalities mark a grim milestone, pushing British deaths in the course of the 10-year war above 400 -- a toll second only to American losses of more than 1,900 troops.
Flags were lowered to half-staff at the main British base in Helmand, and Prime Minister David Cameron called the loss of the six soldiers "desperately sad." The BBC reported that the six had arrived in Afghanistan only a month earlier.
Mr. Cameron, who is to meet next week with President Barack Obama, told the House of Commons that his White House visit would be "an opportunity to make sure that Britain and America ... are absolutely in lockstep about the importance of training up the Afghan army, training up the Afghan police, ... so that the Afghans can take responsibility for the security of their own country, and we can bring our forces home."
The training mission has been complicated, however, by an intensifying pattern of "green-on-blue" shootings -- attacks carried out by members of the Afghan security forces or their affiliates -- which have left at least 11 Western soldiers dead so far this year, including six Americans.
Moreover, talks remain bogged down over terms of an agreement governing any long-term U.S. presence in Afghanistan after 2014, when the NATO combat role is to come to an end.
Other U.S. allies, mindful of the war's political unpopularity at home, accelerated pullbacks after violent episodes. France moved up the timetable for the end to its combat role after four of its troops were killed by an Afghan soldier in January; in February, the Germans abandoned a small base in Afghanistan's north after it came under attack during riots over the burning of copies of the Quran, the Muslim holy book, at a U.S. base.
Another deadly attack happened Wednesday in southern Kandahar province, when a bomb planted on a motorbike exploded at a busy market in Spin Boldak, near the Pakistan border, killing four people.
Several parts of Helmand, including its capital, Lashkar Gah, are now under Afghan police and army security control -- in a push for Afghan forces to take over most combat duties by the end of next year. That coincides with a U.S. drawdown that began late last year and is to gather speed this year.